Tiled waveguide display with a wide field-of-view

ABSTRACT

A waveguide display includes light sources, a source waveguide, an output waveguide, and a controller. Light from each of the light sources is coupled into the source waveguide. The source waveguide includes gratings with a constant period determined based on the conditions for total internal reflection and first order diffraction of the received image light. The emitted image light is coupled into the output waveguide at several entrance locations. The output waveguide outputs expanded image lights at a location offset from the entrance location, and the location/direction of the emitted expanded image light is based in part on the orientation of the light sources. Each of the expanded image light is associated with a field of view of the expanded image light emitted by the output waveguide.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is continuation of co-pending U.S. application Ser. No.15/721,074, filed Sep. 29, 2017, which claims the benefit of U.S.Provisional Application No. 62/432,828, filed Dec. 12, 2016, which isincorporated by reference in its entirety.

BACKGROUND

The disclosure relates generally to near-eye-display systems, and morespecifically to tiled waveguide displays.

Near-eye light field displays project images directly into a user's eye,encompassing both near-eye displays (NEDs) and electronic viewfinders.Conventional near-eye displays (NEDs) generally have a display elementthat generates image light that passes through one or more lenses beforereaching the user's eyes. Additionally, NEDs in virtual reality systemsand/or augmented reality systems are typically required to be compactand light weight, and to provide large exit pupil with a widefield-of-vision for ease of use. However, designing a conventional NEDwith a wide field-of-view can result in rather large lenses, and arelatively bulky and heavy NED.

SUMMARY

A waveguide display is used for presenting media to a user. Thewaveguide display includes a first light source that emits a first imagelight corresponding to a first portion of an image, a second lightsource that emits a second image light corresponding to a second portionof the image that is different than the first portion of the image, asource waveguide including a first entrance area, a second entrancearea, a first exit area, and a second exit area, an output waveguideincluding a third entrance area and a third exit area, and a controllerthat generates and provides scanning instructions to the sourcewaveguide.

The source waveguide in-couples the first image light at the firstentrance area, expands the first image light in at least one dimension,and outputs the expanded first image light via the first exit area. Thesource waveguide in-couples the second image light at the secondentrance area, expands the second image light in a first dimension, andoutputs the expanded second image light via the second exit area. Theoutput waveguide in-couples the first image light and the second imagelight at the third entrance area, expands the expanded first image lightand the expanded second image light in at least one dimension that isorthogonal to the first dimension to generate a portion of a magnifiedimage, and outputs the portion of the magnified image via the third exitarea towards an eyebox. In some configurations, the expanded first imagelight propagates along a first direction and the expanded second imagelight propagates along a second direction opposite to the firstdirection.

In some embodiments, the source waveguide receives the first image lightat a first region and the second image light at a second region, thefirst region and the second region located at an edge of the sourcewaveguide. The first entrance area may include a first coupling elementand the second entrance area may include a second coupling element, eachof the first coupling element and the second coupling element includinggrating elements of a grating period selected based on a refractiveindex of a material forming the source waveguide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a NED, in accordance with an embodiment.

FIG. 2 is a cross-section of the NED illustrated in FIG. 1, inaccordance with an embodiment.

FIG. 3A illustrates an isometric view of a tiled waveguide display, inaccordance with an embodiment.

FIG. 3B illustrates an alternate view of the tiled waveguide display ofFIG. 3A, in accordance with an embodiment.

FIG. 3C illustrates an isometric view of a waveguide display includingmultiple tiled waveguide assemblies, in accordance with an embodiment.

FIG. 4 illustrates a cross-section of a tiled waveguide display, inaccordance with an embodiment.

FIG. 5 is a block diagram of a system including the NED, according to anembodiment.

The figures depict embodiments of the present disclosure for purposes ofillustration only. One skilled in the art will readily recognize fromthe following description that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles, or benefits touted, of the disclosure described herein.

DETAILED DESCRIPTION

A tiled waveguide display (also referred to as a “waveguide display”) isa display that can widen a field of view of image light emitted from thewaveguide display. In some embodiments, the waveguide display isincorporated into, e.g., a near-eye-display (NED) as part of anartificial reality system. The waveguide display includes a tiledwaveguide assembly and an output waveguide. The tiled waveguide assemblyincludes a first light source that emits a first image lightcorresponding to a first portion of an image, a second light source thatemits a second image light corresponding to a second portion of theimage that is different than the first portion of the image, a sourcewaveguide including a first entrance area, a second entrance area, afirst exit area, and a second exit area, and an output waveguideincluding a third entrance area and a third exit area. Light from eachof the first light source and the second light source is coupled intothe source waveguide which emits the image light at specific locationsalong the source waveguide. Each of the first light source and thesecond light source may project a one-dimensional line image to aninfinite viewing distance through a small exit pupil. Theone-dimensional line image can be formed by, for example, using a lineararray of sources and a collimating lens. The source waveguide includes aplurality of grating elements with a constant period determined based onthe conditions for total internal reflection and first order diffractionof the received image light. To form a two-dimensional image, the sourcewaveguide is scanned line-by-line in a direction orthogonal with respectto the one-dimensional line image projected by the first light sourceand the second light source. The source waveguide may be tiled around anaxis of the projected one-dimensional line image to form thetwo-dimensional image. The emitted image light is coupled into theoutput waveguide at a plurality of entrance locations. The outputwaveguide outputs a plurality of expanded image light at a locationoffset from the entrance location, and the location/direction of theemitted expanded image light is based in part on the orientation of thefirst light source and the second light source. Each of the plurality ofexpanded image light is associated with a field of view of the expandedimage light emitted by the output waveguide. In some examples, the totalfield of view of the tiled waveguide display may be a sum of the fieldof view of each of the expanded image light.

Embodiments of the invention may include or be implemented inconjunction with an artificial reality system. Artificial reality is aform of reality that has been adjusted in some manner beforepresentation to a user, which may include, e.g., a virtual reality (VR),an augmented reality (AR), a mixed reality (MR), a hybrid reality, orsome combination and/or derivatives thereof. Artificial reality contentmay include completely generated content or generated content combinedwith captured (e.g., real-world) content. The artificial reality contentmay include video, audio, haptic feedback, or some combination thereof,and any of which may be presented in a single channel or in multiplechannels (such as stereo video that produces a three-dimensional effectto the viewer). Additionally, in some embodiments, artificial realitymay also be associated with applications, products, accessories,services, or some combination thereof, that are used to, e.g., createcontent in an artificial reality and/or are otherwise used in (e.g.,perform activities in) an artificial reality. The artificial realitysystem that provides the artificial reality content may be implementedon various platforms, including a head-mounted display (HMD) connectedto a host computer system, a standalone HMD, a mobile device orcomputing system, or any other hardware platform capable of providingartificial reality content to one or more viewers.

Embodiments of the invention may include or be implemented inconjunction with an artificial reality system. Artificial reality is aform of reality that has been adjusted in some manner beforepresentation to a user, which may include, e.g., a virtual reality (VR),an augmented reality (AR), a mixed reality (MR), a hybrid reality, orsome combination and/or derivatives thereof. Artificial reality contentmay include completely generated content or generated content combinedwith captured (e.g., real-world) content. The artificial reality contentmay include video, audio, haptic feedback, or some combination thereof,and any of which may be presented in a single channel or in multiplechannels (such as stereo video that produces a three-dimensional effectto the viewer). Additionally, in some embodiments, artificial realitymay also be associated with applications, products, accessories,services, or some combination thereof, that are used to, e.g., createcontent in an artificial reality and/or are otherwise used in (e.g.,perform activities in) an artificial reality. The artificial realitysystem that provides the artificial reality content may be implementedon various platforms, including a HMD connected to a host computersystem, a standalone HMD, a mobile device or computing system, or anyother hardware platform capable of providing artificial reality contentto one or more viewers.

FIG. 1 is a diagram of a near-eye-display (NED) 100, in accordance withan embodiment. The NED 100 presents media to a user. Examples of mediapresented by the NED 100 include one or more images, video, audio, orsome combination thereof. In some embodiments, audio is presented via anexternal device (e.g., speakers and/or headphones) that receives audioinformation from the NED 100, a console (not shown), or both, andpresents audio data based on the audio information. The NED 100 isgenerally configured to operate as an artificial reality NED. In someembodiments, the NED 100 may augment views of a physical, real-worldenvironment with computer-generated elements (e.g., images, video,sound, etc.).

The NED 100 shown in FIG. 1 includes a frame 105 and a display 110. Theframe 105 is coupled to one or more optical elements which togetherdisplay media to users. In some embodiments, the frame 105 may representa frame of eye-wear glasses. The display 110 is configured for users tosee the content presented by the NED 100. As discussed below inconjunction with FIG. 2, the display 110 includes at least one waveguidedisplay assembly (not shown) for directing one or more image light to aneye of the user. The waveguide display assembly includes at least one ormore tiled waveguide displays. The waveguide display assembly may alsoinclude, e.g., a stacked waveguide display, a varifocal waveguidedisplay, or some combination thereof. The tiled waveguide display is adisplay that can widen a field of view of the image light emitted fromthe waveguide display. The varifocal waveguide display is a display thatcan adjust a depth of focus of the image light emitted from the tiledwaveguide display.

FIG. 2 is a cross-section 200 of the NED 100 illustrated in FIG. 1, inaccordance with an embodiment. The display 110 includes at least onedisplay assembly 210. An exit pupil 230 is a location where the eye 220is positioned when the user wears the NED 100. For purposes ofillustration, FIG. 2 shows the cross section 200 associated with asingle eye 220 and a single display assembly 210, but in alternativeembodiments not shown, another waveguide display assembly which isseparate from the waveguide display assembly 210 shown in FIG. 2,provides image light to another eye 220 of the user.

The display assembly 210, as illustrated below in FIG. 2, is configuredto direct the image light to the eye 220 through the exit pupil 230. Thedisplay assembly 210 may be composed of one or more materials (e.g.,plastic, glass, etc.) with one or more refractive indices thateffectively minimize the weight and widen a field of view (hereinafterabbreviated as ‘FOV’) of the NED 100. In alternate configurations, theNED 100 includes one or more optical elements between the displayassembly 210 and the eye 220. The optical elements may act to, e.g.,correct aberrations in image light emitted from the display assembly210, magnify image light emitted from the display assembly 210, someother optical adjustment of image light emitted from the displayassembly 210, or some combination thereof. The example for opticalelements may include an aperture, a Fresnel lens, a convex lens, aconcave lens, a filter, or any other suitable optical element thataffects image light.

In some embodiments, the display assembly 210 includes one or more tiledwaveguide displays. In some embodiments, the tiled waveguide display maybe part of the stacked waveguide display, or the varifocal display. Thetiled waveguide display is a display that can widen a field of view ofimage light emitted from the waveguide display. The stacked waveguidedisplay is a polychromatic display (e.g., a red-green-blue (RGB)display) created by stacking the tiled waveguide displays whoserespective monochromatic sources are of different colors.

FIG. 3A illustrates an isometric view of a waveguide display 300, inaccordance with an embodiment. In some embodiments, the waveguidedisplay 300 (may also be referred to as a tiled waveguide display) is acomponent (e.g., display assembly 210) of the NED 100. In alternateembodiments, the waveguide display 300 is part of some other NED, orother system that directs display image light to a particular location.

The waveguide display 300 includes at least a tiled waveguide assembly310, an output waveguide 320, and a controller 330. For purposes ofillustration, FIG. 3A shows the waveguide display 300 associated with asingle eye 220, but in some embodiments, another waveguide displayseparate (or partially separate) from the waveguide display 300,provides image light to another eye of the user. In a partially separatesystem, one or more components may be shared between waveguide displaysfor each eye.

The tiled waveguide assembly 310 generates image light. The tiledwaveguide assembly 310 includes a plurality of optical sources, a sourcewaveguide, and a controller (e.g., as further described below withregard to FIG. 4). The tiled waveguide assembly 310 generates andoutputs image light 340 to a coupling element 350 of the outputwaveguide 320.

The output waveguide 320 is an optical waveguide that outputs imagelight to an eye 220 of a user. The output waveguide 320 receives theimage light 340 at one or more coupling elements 350, and guides thereceived input image light to one or more decoupling elements 360. Insome embodiments, the coupling element 350 couples the image light 340from the tiled waveguide assembly 310 into the output waveguide 320. Thecoupling element 350 may be, e.g., a diffraction grating, a holographicgrating, some other element that couples the image light 340 into theoutput waveguide 320, or some combination thereof. For example, inembodiments where the coupling element 350 is diffraction grating, thepitch of the diffraction grating is chosen such that total internalreflection occurs, and the image light 340 propagates internally towardthe decoupling element 360. For example, the pitch of the diffractiongrating may be in the range of 300 nm to 600 nm.

The decoupling element 360 decouples the total internally reflectedimage light from the output waveguide 320. The decoupling element 360may be, e.g., a diffraction grating, a holographic grating, some otherelement that decouples image light out of the output waveguide 320, orsome combination thereof. For example, in embodiments where thedecoupling element 360 is a diffraction grating, the pitch of thediffraction grating is chosen to cause incident image light to exit theoutput waveguide 320. For example, the pitch of the diffraction gratingmay be in the range of 300 nm to 600 nm. The pitch of the diffractiongrating is chosen such that the image light 340 from the plurality ofoptical sources undergoes a total internal reflection inside the outputwaveguide 320 without leakage through higher order diffraction (e.g.second reflected order). An orientation and position of the image lightexiting from the output waveguide 320 is controlled by changing anorientation and position of the image light 340 entering the couplingelement 350. In some embodiments, the direction of the image lightexiting from the output waveguide 320 is same as the direction of theimage light 340. In one example, the position of the image light exitingfrom the output waveguide 320 is controlled by the location of theplurality of optical sources of the tiled waveguide assembly 310, thelocation of the coupling element 350 and the location of the decouplingelement 360. Any change in the orientation of at least an optical sourceto cover a portion of the total FOV causes the image light exiting fromthe output waveguide 320 to cover the same portion of the total FOV. Thetotal FOV is obtained by using a plurality of optical sources that coverthe entire FOV. In addition, the total FOV is a function of a refractiveindex of the output waveguide 320, the pitch of the diffraction grating,a total number of optical sources of the tiled waveguide assembly 310,and a requirement of having no leakage light from the output waveguide320 via second order diffraction.

The output waveguide 320 may be composed of one or more materials thatfacilitate total internal reflection of the image light 340. The outputwaveguide 320 may be composed of e.g., silicon, plastic, glass, orpolymers, or some combination thereof. The output waveguide 320 has arelatively small form factor. For example, the output waveguide 320 maybe approximately 50 mm wide along X-dimension, 30 mm long alongY-dimension and 0.5-1 mm thick along Z-dimension.

The controller 330 controls the scanning operations of the tiledwaveguide assembly 310. The controller 330 determines displayinstructions for the tiled waveguide assembly 310 based at least on theone or more display instructions. Display instructions are instructionsto render one or more images. In some embodiments, display instructionsmay simply be an image file (e.g., bitmap). The display instructions maybe received from, e.g., a console of a VR system (e.g., as describedbelow in conjunction with FIG. 5). Display instructions are instructionsused by the tiled waveguide assembly 310 to generate image light 340.The display instructions may include, e.g., a type of a source of imagelight (e.g. monochromatic, polychromatic), an identifier for aparticular light source assembly, an identifier for a particular tiledwaveguide assembly, a scanning rate, an orientation of the source, oneor more illumination parameters (described below with reference to FIG.4), or some combination thereof. The controller 330 receives displayinstructions that controls the orientation of the expanded light 370associated with a total field of view of the image light exiting theoutput waveguide 320. For example, the total field of view can be a sumof a field of view of each of the plurality of optical sources of thetiled waveguide assembly 310. In some embodiments, the total field ofview can be a weighted sum of the field of view of each of the pluralityof optical sources with the weights of each of the individual field ofview determined based on an amount of overlap between the field of viewfrom different optical sources. In some embodiments, the controller 330also receives display instructions that includes identifier informationto select the tiled waveguide assembly that receives the displayinstructions. The controller 330 includes a combination of hardware,software, and/or firmware not shown here so as not to obscure otheraspects of the disclosure.

FIG. 3B illustrates an alternate view of the waveguide display 300, inaccordance with an embodiment. FIG. 3B is an embodiment of the waveguidedisplay 300 of FIG. 3A, and all the details described above withreference to FIG. 3A apply to FIG. 3B as well. FIG. 3B illustrates thepropagation of one or more reflected image light 315 through the tiledwaveguide assembly 310.

The tiled waveguide assembly 310 receives image light from each of theoptical source assemblies 410A and 410B, described in detail below inconjunction with FIG. 4, and expands each of the image light along twoopposite directions. The tiled waveguide assembly 310 generates areflected light 315A that undergoes total internal reflection andpropagates generally along a negative X-dimension. The tiled waveguideassembly 310 generates a reflected light 315B that undergoes totalinternal reflection and propagates generally along a positiveX-dimension. The direction of propagation of the reflected light 315 isbased on the pitch of the diffraction gratings and the occurrence oftotal internal reflection of the image light from each of the pluralityof optical sources for a desired range of angles of incidence to achievea specific order of diffraction of interest. For example, to achieve apositive first order of diffraction (+1), the pitch of diffractiongrating of the coupling element 350 is designed such that the reflectedlight 315B propagates along the positive X direction. Similarly, thepitch of another diffraction grating of the coupling element 350 isdesigned such that the reflected light 315A propagates along thenegative X direction to achieve a negative first order of diffraction(−1). The tiled waveguide assembly 310 generates and outputs an imagelight 340 to the output waveguide 320. In some embodiments, the imagelight 340 includes an image light 340A and an image light 340B. Theimage light 340 undergoes total internal reflection at the outputwaveguide 320 as illustrated in FIG. 3B. The image light 340 decouplesthrough the decoupling element 360 as expanded light 370 and reaches theeye 220. In some embodiments, the expanded light 370A represents anexpanded image light emitted at a perpendicular direction to the surfaceof the output waveguide 320. The expanded light 370B represents an imagelight emitted at an angle of inclination to the surface of the outputwaveguide 320. In some configurations, the angle of inclination of theexpanded image light 370B can range from −30 degrees to +30 degrees.

FIG. 3C an isometric view of a waveguide display 380 including multipletiled waveguide assemblies 310A and 310B, in accordance with anembodiment. FIG. 3C is an embodiment of the waveguide display 300 ofFIG. 3A. The waveguide display 380 of FIG. 3C includes a tiled waveguideassembly 310A, a tiled waveguide assembly 310B, an output waveguide320B, and the controller 330. The tiled waveguide assembly 310A and 310Bare substantially similar to the tiled waveguide assembly 310 of FIG.3A. The output waveguide 320B is structurally similar to the outputwaveguide 320 of FIG. 3A except for a coupling element 350B. Thecoupling element 350B is an embodiment of the coupling element 350 ofFIG. 3A.

The tiled waveguide assembly 310A outputs an image light 340A to thecoupling element 350A. The tiled waveguide assembly 310B outputs animage light 340B to the coupling element 350B. The image light 340A and340B are embodiments of the image light 340 of FIG. 3A. In the exampleof FIG. 3C, the tiled waveguide assembly 310A is oriented along thex-dimension and the tiled waveguide assembly 310B is oriented along thesame x-dimension at an offset from the tiled waveguide assembly 310A. Insome embodiments, the offset is determined by a desired size of an eyebox, the total FOV, and an eye relief distance. The offset is alsoassociated with defining how large of an output area (e.g. 40 mm×30 mm)is needed to give the desired size of the eye box for a given total FOV,and the eye relief distance.

FIG. 4 illustrates a cross-section 400 of the waveguide assembly 300, inaccordance with an embodiment. The cross-section 400 of the tiledwaveguide assembly 300 includes a source assembly 410A, a sourceassembly 410B, and a source waveguide 430.

The source assemblies 410A and 410B generate light in accordance withdisplay instructions from the controller 330. The source assembly 410Aincludes a source 440A, and an optics system 450A. The source 440A is asource of light that generates at least a coherent or partially coherentimage light. The source 440A may be, e.g., a laser diode, a verticalcavity surface emitting laser, a light emitting diode, a tunable laser,or some other light source that emits coherent or partially coherentlight. The source 440A emits light in a visible band (e.g., from about390 nm to 700 nm), and it may emit light that is continuous or pulsed.In some embodiments, the source 440A may be a laser that emits light ata particular wavelength (e.g., 532 nanometers). The source 440A emitslight in accordance with one or more illumination parameters receivedfrom the controller 330. An illumination parameter is an instructionused by the source 440A to generate light. An illumination parameter mayinclude, e.g., source wavelength, pulse rate, pulse amplitude, beam type(continuous or pulsed), other parameter(s) that affect the emittedlight, or some combination thereof. The source assembly 410B isstructurally similar to the source assembly 410A except for theidentifier information in the display instructions from the controller330.

In some embodiments, the source assembly 410A and the source assembly410B are located on opposite ends of the source waveguide 430. Thesource assembly 410A generates an image light directed along thenegative z-dimension and in-coupled by the source waveguide 430 so as topropagate toward the negative x-dimension. The source assembly 410Bgenerates an image light directed along the positive z-dimension andin-coupled by the source waveguide 430 so as to propagate toward thepositive x-dimension.

The optics system 450 includes one or more optical components thatcondition the light from the source 440. Conditioning light from thesource 440 may include, e.g., expanding, collimating, adjustingorientation in accordance with instructions from the controller 330,some other adjustment of the light, or some combination thereof. The oneor more optical components may include, e.g., lenses, mirrors,apertures, gratings, or some combination thereof. Light emitted from theoptics system 450 (and also the source assembly 410) is referred to asimage light 455. The optics system 450 outputs the image light 455toward the source waveguide 430.

The source waveguide 430 is an optical waveguide. The source waveguide430 may be composed of one or more materials that facilitate totalinternal reflection of the image light 455. The source waveguide 430 maybe composed of e.g., silicon, plastic, glass, or polymers, a materialwith an index of refraction below 2, or some combination thereof. Thesource waveguide 430 has a relatively small form factor. For example,the source waveguide 430 may be approximately 50 mm long alongX-dimension, 3 mm wide along Y-dimension, and 0.5-1 mm thick alongZ-dimension.

The source waveguide 430 includes a coupling element 460A and adecoupling element 470. The source waveguide 430 receives the imagelight 455A emitted from the source assembly 410A at the coupling element460A. The coupling element 460A couples the image light 455A from thesource assembly 410A into the source waveguide 430. The coupling element460A may be, e.g., a diffraction grating, a holographic grating, areflective surface, a prismatic structure, a side or edge of the body ofthe source waveguide 430, some other element that couples the imagelight 455A into the source waveguide 430, or some combination thereof.For example, in embodiments where the coupling element 460A isdiffraction grating, the pitch of the diffraction grating is chosen suchthat total internal reflection occurs, and the image light 455Apropagates internally toward the decoupling element 470. For example,the pitch of the diffraction grating may be in the range of 300 nm to600 nm.

The decoupling element 470 decouples the total internally reflectedimage light 455A from the source waveguide 430. In some embodiments, thedecoupling element 470 includes a variation in the design of thediffraction grating (e.g. pitch) so that decoupling of an image light ismore efficient to a given range of angles of incidence in certain partsof the diffraction grating. The decoupling element 470 may be, e.g., adiffraction grating, a holographic grating, a reflective surface, aprismatic structure, a side or edge of the body of the source waveguide430, some other element that decouples image light out of the sourcewaveguide 430, or some combination thereof. For example, in embodimentswhere the decoupling element 470 is a diffraction grating, the pitch ofthe diffraction grating is chosen to cause incident image light to exitthe source waveguide 430. An orientation of the image light exiting fromthe source waveguide 430 may be altered by varying the orientation ofthe image light exiting the source assembly 410A, varying an orientationof the source assembly 410A, or some combination thereof. For example,the pitch of the diffraction grating may be in the range of 300 nm to600 nm.

In a typical near-eye-display (NED) system using diffraction gratings ascoupling elements, the limit for the FOV is based on satisfying twophysical conditions: (1) an occurrence of total internal reflection ofimage light coupled into the source waveguide 430 and (2) an existenceof a first order diffraction of the coupling element 460A and 460B overthe FOV of their respective image sources. Conventional methods used bythe NED systems based on diffracting gratings rely on satisfying theabove two physical conditions in order to achieve a large FOV (e.g.above 40 degrees) by using materials with a high refractive index,wherein the said methods add significantly heavy and expensivecomponents to the NED system. In contrast, the waveguide display 300relies on splitting the FOV into two half spaces by separating thecoupling elements 460A and 460B, each of the coupling elementsconfigured to receive the image light 455A and the image light 455B,respectively. Accordingly, the value of the pitch of the diffractiongrating inside the coupling element 460A determines the limit for thefirst order diffraction of the image light 455A and the limit for thetotal internal reflection of the image light 455A inside the sourcewaveguide 430.

As both the coupling element 460A and the coupling element 460B reflectan image light to the same decoupling element 470, the pitch of thediffraction grating is the same in order to form a non-distorted image.In this case, the optical sources are configured to provide half of theFOV, for example, the image light 455A provides from −FOV/2 to 0 and theimage light 455B provides from 0 to FOV/2. In a second example, theimage light 455A provides from 0 to FOV/2 and the image light 455Bprovides from −FOV/2 to 0. The pitch of the diffraction grating isselected so that the FOV corresponding to the image light 455A iscoupled into a positive first (+1) order of diffraction and the FOV ofthe image light 455B is coupled into a negative first (−1) order ofdiffraction. To maximize the brightness of the display presented to theuser's eye, the grating profile of the coupling element 460A and thecoupling element 460B are designed separately to optimize the amount oflight coupled into the desired diffraction orders, respectively. Inaddition, the pitch of the diffraction grating may be adjusted tominimize light leakage out of the source waveguide 430 via diffractionto higher order diffracted modes.

The decoupling element 470 outputs the image light 440A and the imagelight 440B to the output waveguide 320. The value of the pitch of thediffraction grating inside the decoupling element 470 is selected to beequal to that of the coupling element 460A and the coupling element 460Bin order to form an undistorted image for the image light in the displaypresented to the user's eyes. The grating profile is designed so thatlight is decoupled from the source waveguide 430 partially in eachinterception of the image light with the decoupling element 470. Themultiple partial diffractions of the light with the decoupling element470 results in the total expansion along the x-dimension of the imagelight 440.

The image light 440A exiting the source waveguide 430 is expanded atleast along one dimension (e.g., may be elongated along x-dimension).The image light 440 couples to an output waveguide 320 as describedabove with reference to FIG. 3A.

In some embodiments, the decoupling element 470 has an extended lengthin the direction of propagation of an image light trapped inside thesource waveguide 430. The decoupling element 470 may represent an exitpupil of the source waveguide 430.

The controller 330 controls the source assembly 410A by providingdisplay instructions to the source assembly 410A. The displayinstructions cause the source assembly 410A to render light such thatimage light exiting the decoupling element 360 of the output waveguide320 scans out one or more 2D images. For example, the displayinstructions may cause the tiled waveguide assembly 310 to generate atwo-dimensional image from a 1-D array pattern of image light generatedby the source assembly 410 (e.g. using a 1-D array of MicroLEDs and acollimating lens). The controller 330 controls the source waveguide 430by providing scanning instructions to the source waveguide 430. Thescanning instructions cause the source waveguide 430 to perform ascanning operation of the source waveguide 430, in accordance with ascan pattern (e.g., raster, interlaced, etc.) The display instructionscontrol an intensity of light emitted from the source 440, and theoptics system 450 scans out the image by rapidly adjusting orientationof the emitted light. If done fast enough, a human eye integrates thescanned pattern into a single 2D image. The display instructions alsocontrol a direction (e.g. clock-wise or anti-clockwise) and a speed ofrotation of the source waveguide 430.

In some configurations, the total field of view of the tiled waveguidedisplay 310 can be determined from the sum of the field of viewcorresponding to the image light 455A and the image light 455B. In atypical NED system, the field of view is restricted to half of the totalfield of view of the tiled waveguide display 310 as there is nosplitting of the field of view using two source assemblies. In addition,the tiled waveguide display 310 has a relaxation in the form factor ofthe light source assemblies 410A and 410B as the field of view for eachof the sources 440A and 440B is half of the field of view for awaveguide display with a single light source.

FIG. 5 is a block diagram of a system 500 including the NED 100,according to an embodiment. The system 500 shown by FIG. 5 comprises theNED 100, an imaging device 535, and a VR input interface 540 that areeach coupled to the VR console 510. While FIG. 5 shows an example system500 including one NED 100, one imaging device 535, and one VR inputinterface 540, in other embodiments, any number of these components maybe included in the system 500. For example, there may be multiple NEDs100 each having an associated VR input interface 540 and being monitoredby one or more imaging devices 535, with each NED 100, VR inputinterface 540, and imaging devices 535 communicating with the VR console510. In alternative configurations, different and/or additionalcomponents may be included in the system 500. Similarly, functionalityof one or more of the components can be distributed among the componentsin a different manner than is described here. For example, some or allof the functionality of the VR console 510 may be contained within theNED 100. Additionally, in some embodiments the VR system 500 may bemodified to include other system environments, such as an AR systemenvironment, or more generally an artificial reality environment.

The IMU 130 is an electronic device that generates fast calibration dataindicating an estimated position of the NED 100 relative to an initialposition of the NED 100 based on measurement signals received from oneor more of the position sensors 125. A position sensor 125 generates oneor more measurement signals in response to motion of the NED 100.Examples of position sensors 125 include: one or more accelerometers,one or more gyroscopes, one or more magnetometers, another suitable typeof sensor that detects motion, a type of sensor used for errorcorrection of the IMU 130, or some combination thereof. The positionsensors 125 may be located external to the IMU 130, internal to the IMU130, or some combination thereof. In the embodiment shown by FIG. 5, theposition sensors 125 are located within the IMU 130, and neither the IMU130 nor the position sensors 125 are visible to the user (e.g., locatedbeneath an outer surface of the NED 100).

Based on the one or more measurement signals generated by the one ormore position sensors 125, the IMU 130 generates fast calibration dataindicating an estimated position of the NED 100 relative to an initialposition of the NED 100. For example, the position sensors 125 includemultiple accelerometers to measure translational motion (forward/back,up/down, left/right) and multiple gyroscopes to measure rotationalmotion (e.g., pitch, yaw, roll). In some embodiments, the IMU 130rapidly samples the measurement signals from various position sensors125 and calculates the estimated position of the NED 100 from thesampled data. For example, the IMU 130 integrates the measurementsignals received from one or more accelerometers over time to estimate avelocity vector and integrates the velocity vector over time todetermine an estimated position of a reference point on the NED 100. Thereference point is a point that may be used to describe the position ofthe NED 100. While the reference point may generally be defined as apoint in space; however, in practice, the reference point is defined asa point within the NED 100 (e.g., the reference point 115 representing acenter of the IMU 130).

The imaging device 535 generates slow calibration data in accordancewith calibration parameters received from the VR console 510. Theimaging device 535 may include one or more cameras, one or more videocameras, one or more filters (e.g., used to increase signal to noiseratio), or any combination thereof. The imaging device 535 is configuredto detect image light emitted or reflected in the FOV of the imagingdevice 535. In embodiments where the NED 100 include passive elements(e.g., a retroreflector), the imaging device 535 may retro-reflect theimage light towards the image light source in the imaging device 535.Slow calibration data is communicated from the imaging device 535 to theVR console 510, and the imaging device 535 receives one or morecalibration parameters from the VR console 510 to adjust one or moreimaging parameters (e.g., focal length, focus, frame rate, ISO, sensortemperature, shutter speed, aperture, etc.).

The VR input interface 540 is a device that allows a user to send actionrequests to the VR console 510. An action request is a request toperform a particular action. For example, an action request may be tostart or end an application or to perform a particular action within theapplication. The VR input interface 540 may include one or more inputdevices. Example input devices include: a keyboard, a mouse, a gamecontroller, or any other suitable device for receiving action requestsand communicating the received action requests to the VR console 510. Anaction request received by the VR input interface 540 is communicated tothe VR console 510, which performs an action corresponding to the actionrequest. In some embodiments, the VR input interface 540 may providehaptic feedback to the user in accordance with instructions receivedfrom the VR console 510. For example, haptic feedback is provided whenan action request is received, or the VR console 510 communicatesinstructions to the VR input interface 540 causing the VR inputinterface 540 to generate haptic feedback when the VR console 510performs an action.

The VR console 510 provides media to the NED 100 for presentation to theuser in accordance with information received from one or more of: theimaging device 535, the NED 100, and the VR input interface 540. In theexample shown in FIG. 5, the VR console 510 includes an applicationstore 545, a tracking module 550, and a VR engine 555. Some embodimentsof the VR console 510 have different modules than those described inconjunction with FIG. 5. Similarly, the functions further describedbelow may be distributed among components of the VR console 510 in adifferent manner than is described here.

The application store 545 stores one or more applications for executionby the VR console 510. An application is a group of instructions, thatwhen executed by a processor, generates content for presentation to theuser. Content generated by an application may be in response to inputsreceived from the user via movement of the NED 100 or the VR inputinterface 540. Examples of applications include: gaming applications,conferencing applications, video playback application, or other suitableapplications.

The tracking module 550 calibrates the VR system 500 using one or morecalibration parameters and may adjust one or more calibration parametersto reduce error in determination of the position of the NED 100. Forexample, the tracking module 550 adjusts the focus of the imaging device535 to obtain a more accurate position on the VR headset. Moreover,calibration performed by the tracking module 550 also accounts forinformation received from the IMU 530. Additionally, if tracking of theNED 100 is lost, the tracking module 550 re-calibrates some or theentire system environment 500.

The tracking module 550 tracks movements of the NED 100 using slowcalibration information from the imaging device 535. The tracking module550 also determines positions of a reference point of the NED 100 usingposition information from the fast calibration information.Additionally, in some embodiments, the tracking module 550 may useportions of the fast calibration information, the slow calibrationinformation, or some combination thereof, to predict a future locationof the NED 100. The tracking module 550 provides the estimated orpredicted future position of the NED 100 to the VR engine 555.

The VR engine 555 executes applications within the system 500 andreceives position information, acceleration information, velocityinformation, predicted future positions, or some combination thereof ofthe NED 100 from the tracking module 550. In some embodiments, theinformation received by the VR engine 555 may be used for producing asignal (e.g., display instructions) to the waveguide display assembly515 that determines the type of content presented to the user. Forexample, if the received information indicates that the user has lookedto the left, the VR engine 555 generates content for the NED 100 thatmirrors the user's movement in a virtual environment by determining thetype of source and the waveguide that operate in the waveguide displayassembly 515. For example, the VR engine 555 may produce a displayinstruction that would cause the waveguide display assembly 515 togenerate content with red, green, and blue color. Additionally, the VRengine 555 performs an action within an application executing on the VRconsole 510 in response to an action request received from the VR inputinterface 540 and provides feedback to the user that the action wasperformed. The provided feedback may be visual or audible feedback viathe NED 100 or haptic feedback via the VR input interface 540.

Additional Configuration Information

The foregoing description of the embodiments of the disclosure has beenpresented for the purpose of illustration; it is not intended to beexhaustive or to limit the disclosure to the precise forms disclosed.Persons skilled in the relevant art can appreciate that manymodifications and variations are possible in light of the abovedisclosure.

Some portions of this description describe the embodiments of thedisclosure in terms of algorithms and symbolic representations ofoperations on information. These algorithmic descriptions andrepresentations are commonly used by those skilled in the dataprocessing arts to convey the substance of their work effectively toothers skilled in the art. These operations, while describedfunctionally, computationally, or logically, are understood to beimplemented by computer programs or equivalent electrical circuits,microcode, or the like. Furthermore, it has also proven convenient attimes, to refer to these arrangements of operations as modules, withoutloss of generality. The described operations and their associatedmodules may be embodied in software, firmware, hardware, or anycombinations thereof.

Any of the steps, operations, or processes described herein may beperformed or implemented with one or more hardware or software modules,alone or in combination with other devices. In one embodiment, asoftware module is implemented with a computer program productcomprising a computer-readable medium containing computer program code,which can be executed by a computer processor for performing any or allof the steps, operations, or processes described.

Embodiments of the disclosure may also relate to an apparatus forperforming the operations herein. This apparatus may be speciallyconstructed for the required purposes, and/or it may comprise ageneral-purpose computing device selectively activated or reconfiguredby a computer program stored in the computer. Such a computer programmay be stored in a non-transitory, tangible computer readable storagemedium, or any type of media suitable for storing electronicinstructions, which may be coupled to a computer system bus.Furthermore, any computing systems referred to in the specification mayinclude a single processor or may be architectures employing multipleprocessor designs for increased computing capability.

Embodiments of the disclosure may also relate to a product that isproduced by a computing process described herein. Such a product maycomprise information resulting from a computing process, where theinformation is stored on a non-transitory, tangible computer readablestorage medium and may include any embodiment of a computer programproduct or other data combination described herein.

Finally, the language used in the specification has been principallyselected for readability and instructional purposes, and it may not havebeen selected to delineate or circumscribe the inventive subject matter.It is therefore intended that the scope of the disclosure be limited notby this detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsis intended to be illustrative, but not limiting, of the scope of thedisclosure, which is set forth in the following claims.

1. A waveguide display, comprising: a first light source configured toemit first light; a second light source configured to emit second light;and a waveguide to receive the first light and the second light and tooutput a first image light and a second image light, the waveguideincluding an outcoupling grating configured to outcouple the first imagelight at a first field-of-view (FOV) and to outcouple the second imagelight at a second FOV, the first image light corresponding to the firstlight and a first portion of an image, and the second image lightcorresponding to the second light and a second portion of the image. 2.The waveguide display of claim 1, wherein a total FOV of the waveguidedisplay is a sum of the first FOV and the second FOV.
 3. The waveguidedisplay of claim 1, wherein a total FOV of the waveguide display is asum of the first FOV weighted by a first weight and the second FOVweighted by a second weight, the first weight and the second weightdetermined based on an amount of overlap between the first FOV and thesecond FOV.
 4. The waveguide display of claim 1, wherein each of thefirst FOV and the second FOV is a function of a refractive index of amaterial forming the first waveguide.
 5. The waveguide display of claim1, wherein the first waveguide is configured to expand each of the firstlight and the second light along two opposite directions.
 6. Thewaveguide display of claim 1, wherein the first waveguide includes anentrance area comprises a first coupling element to in-couple the firstlight and a second coupling element to in-couple the second light, eachof the first coupling element and the second coupling element comprisinga plurality of gratings of a grating period selected based on arefractive index of a material forming the first waveguide.
 7. Thewaveguide display of claim 1, further comprising a second waveguideconfigured to direct the first light from the first light source to thefirst waveguide and to direct the second light from the second lightsource to the first waveguide.
 8. The waveguide display of claim 7,wherein the second waveguide is configured to receive the first light ata first region and to receive the second light at a second region, thefirst region and the second region located at opposite edges of thesecond waveguide.
 9. The waveguide display of claim 8, wherein an offsetbetween the first region and the second region is determined accordingto at least one of a desired size of an eye box, a total FOV, and an eyerelief distance.
 10. The waveguide display of claim 8, wherein the firstimage light and the second image light propagate along oppositedirections around an axis, and the opposite edges of the secondwaveguide are oriented along the axis.
 11. The waveguide display ofclaim 7, wherein the second waveguide is configured to in-couple thefirst light at the first entrance area and to in-couple the second lightat the second entrance area, the first entrance area including a firstcoupling element and the second entrance area including a secondcoupling element, each of the first coupling element and the secondcoupling element further comprising a plurality of grating elements of agrating period selected based on a refractive index of a materialforming the second waveguide.
 12. The waveguide display of claim 7,wherein each of the first light and the second light undergoes a totalinternal reflection or a first order diffraction inside the secondwaveguide.
 13. The waveguide display of claim 1, further comprising asecond waveguide and a third waveguide, the second waveguide expandingalong a first dimension and the third waveguide expanding along a seconddimension orthogonal to the first dimension.
 14. A source waveguideassembly comprising: a waveguide body; a first entrance area configuredto in-couple a first image light corresponding to a first portion of animage from a first light source into the waveguide body; a secondentrance area configured to in-couple a second image light correspondingto a second portion of an image from a second light source into thewaveguide body, the second portion of the image different than the firstportion of the image; a first exit area configured to output expandedfirst image light, the expanded first image light being the first imagelight expanded along two opposite directions; and a second exit areaconfigured to output expanded second image light, the expanded secondimage light being the second image light expanded along the two oppositedirections.
 15. The source waveguide assembly of claim 14, wherein thefirst entrance area and the second entrance area are located at oppositeedges of the source waveguide assembly.
 16. The source waveguideassembly of claim 14, wherein the first entrance area comprises a firstcoupling element and the second entrance area comprises a secondcoupling element, each of the first coupling element and the secondcoupling element comprising a plurality of grating elements of a gratingperiod selected based on a refractive index of a material forming thewaveguide body.
 17. The source waveguide assembly of claim 14, whereinthe expanded first image light propagates along a first direction of thetwo opposite directions and the expanded second image light propagatesalong a second direction of the two opposite directions, the seconddirection opposite to the first direction.
 18. The source waveguideassembly of claim 14, wherein each of the in-coupled first image lightand the in-coupled second image light undergoes a total internalreflection inside the waveguide body.
 19. The source waveguide assemblyof claim 14, wherein each of the in-coupled first image light and thein-coupled second image light undergoes a first order diffraction insidethe waveguide body.
 20. The source waveguide assembly of claim 14,wherein the further comprising a second waveguide body, the firstwaveguide body expanding along a first dimension and the secondwaveguide body expanding along a second dimension orthogonal to thefirst dimension.